// 

function accountsMerge(){
    let rowLen = accounts.length
    for(let row=0; row<rowLen-1; row++){
        for(let row2=row+1; row2<rowLen; row2++){
            compare(accounts[row], accounts[row2])
        }
    }
}

function compare(arr1, arr2){
    console.log(arr1, arr2)
}

let accounts = [
    ["John", "johnsmith@mail.com", "john00@mail.com"], 
    ["John", "johnnybravo@mail.com"], 
    ["John", "johnsmith@mail.com", "john_newyork@mail.com"], 
    ["Mary", "mary@mail.com"]
]
accountsMerge(accounts)
